Johannesburg - Any trade union wanting to leave Cosatu will first have to deal with the SA Communist Party, says SACP general secretary Blade Nzimande.
"If some [union] leaders think that they are going to take certain affiliates out of Cosatu, they will find the communist party first," he said in Benoni on the East Rand on Thursday.
"Those who are threatening to walk out...they will first have to open this red door."
Nzimande was addressing Police and Prisons Civil Rights Union members at their second national political school.
He said affiliates of the Congress of SA Trade Unions should not contemplate leaving the federation.
"Those who are planning to do so, they are part of the enemy that wants to destroy our revolution.
"There can be no problem that is bigger than the unity of Cosatu."
The National Union of Metalworkers of SA has expressed it lack of confidence in Cosatu president Sidumo Dlamini following the suspension of general secretary Zwelinzima Vavi.
It reportedly said it would consider leaving Cosatu.
Cosatu announced on Thursday last week that Vavi had been put on special leave pending the outcome of a disciplinary hearing into an affair he had with a junior Cosatu employee.
The employee last month accused Vavi of rape and he admitted to having a consensual affair with her.
The woman subsequently withdrew a sexual harassment complaint against him.
Nzimande said the SACP was concerned the "sex scandal" could derail Cosatu affiliates.
He said Cosatu's enemies could exploit it to cause divisions.
"It [Cosatu] must not be derailed from dealing with the challenges inside itself."
He said problems in Cosatu could not be reduced to "personalities, names and conspiracies".
The "liberal idea" that the state was inherently bad and constantly had to be criticised had to be resisted.
"That is why in our universities and the media, in order to prove that we are truly independent, we must attack the government and the ANC and then you will get kudos," he said.
"Most of us here campaigned for this government in 2009.
"This is our government, no matter what problems it has, it is your government."